This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Peanuts and tree nuts are the most allergenic foods in children and adults, and allergic reactions to these foods can be severe and sometimes fatal. Peanut and nut allergy, unlike allergy to milk, egg, soy and wheat, are rarely outgrown;however, a recent study found a significantly higher percentage of children outgrew their peanut allergy than previously appreciated. While longitudinal studies have shown that milk, egg and soy allergies detected early in life often resolve, only one published report on peanut allergy suggests that this allergy can be "outgrown". The purpose of this study is to test our hypothesis that 10-20% of children with early onset peanut or tree nut allergy become tolerant later in life, and confirm our previous observations that quantitation of antigen-specific IgE antibodies by CAP-RAST FEI (Pharmacia &Upjohn Diagnostics) is a good predictor of clinical reactivity.